Electrical Performance Degradation Model and Residual Electrical Life Prediction for AC Contactor

Abstract

The electrical performance of ac contactor degrades under electric load stress, and the degradation data contains the information concerning the residual electrical life (REL). This article proposes an online reliability evaluation method that relates contact erosion loss (CEL) to electric load stress, performance degradation process, and electrical life prediction. First, the degradation variable of normal distribution is constructed by segmenting accumulation of CEL, and a degradation model based on Wiener process is established. With the knowledge of the first accumulation of CEL beyond failure threshold, the probability density function (PDF) of REL for ac contactor is presented, and the point estimation value and an interval estimation value of REL are calculated. Second, a simulation electrical life test is conducted using Monte Carlo method, and results show that the electrical performance degradation model and the prediction method of REL raised in this article are effective. Finally, CELs weighed in the electrical life test are applied in the prediction process of REL of ac contactor and the prediction error is proven acceptable in practical application. Compared with the neural network-based methods, the proposed method provides an intuitive and simple mathematical model with clear physical interpretations.